Is an LDA w/GS a "Precision" approach?
Garner Miller
going for an airline interview next week, and rumor has it they're
going to whip out an approach plate with an "LDA with Glideslope"
approach.
Nothing really unusual about such a beast... it's basically just an ILS
offset from the runway by more than a couple degrees, and [other than
turning before you land] is flown the same way, complete with a
Decision Altitude (DA) vs. an MDA. In this case, I think it'll
probably be the one to Runway 6 in Roanoke, VA (ROA).
The tricky part: I hear the question will be, "Is this a precision
approach?"
I find conflicting information in the FAR and AIM. My answer would
have to be yes, based on the definition found both in FAR 1.1 and in
the Pilot/Controller glossary: "A precision approach is a standard
instrument approach procedure in which an electronic glide slope is
provider, such as ILS and PAR."
That seems pretty cut and dry to me, but then I was pointed to the AIM,
section 5-4-5-(a)-5:
"TERPS criteria are provided for the following type of instrument
approach procedures:
(a) Precision approaches where an electronic glide slope is provided
(PAR and ILS) and,
(b) Nonprecision approaches where glide slope information is not
provided (*all* approaches except PAR and ILS)." [emphasis mine]
I'd say the preponderance of the evidence leans toward an LDA/GS being
a precision approach (by its definition in 1.1), but I'd appreciate
your thoughts.
Why such a question would be asked of an applicant, I don't know (other
than to see if he knows where to find things in the FAR/AIM), but it's
got my curiosity piqued.
Thanks in advance.
--
Garner R. Miller, CFII/MEI
Pilot, US Airways Express, Portland, ME
http://www.netstreet.net/~garner/
Please don't e-mail me a copy of your usenet reply.
Bob Noel
<gar...@netstreet.net> wrote:
> OK, I'm in need of some 100% trivial information. I have a friend
> going for an airline interview next week, and rumor has it they're
> going to whip out an approach plate with an "LDA with Glideslope"
> approach.
[snip]
>
> The tricky part: I hear the question will be, "Is this a precision
> approach?"
fwiw - my vote is: yes, it's a precision approach, by definition.
I'll pose the question to a friend at work that designed
approaches in a past life.
--
Bob
(I think people can figure out how to email me...)
(replace ihatessppaamm with my name (rnoel) and hw1 with mediaone)
Garner Miller
<jpgoode_...@flash.net> wrote:
> I for one argued that [a LDA w/Glideslope] was a precision
> approach, citing your exact reasoning. But as it turns out, I was
> wrong. According to TERPS criteria, which are the only criteria that
> really matter when you get right down to it, a LDA/GS approach is a
> *non-precision* approach in spite of the electronic glideslope and the
> DA. This straight from the TERPS-meister, Wally Roberts.
That's so weird... but I guess it makes some sense. I just wish the
definition in 1.1 and the Pilot/Controller glossary didn't so plainly
disagree, as it makes it a harder point to prove either way (as you
found out). If, for some reason, you were using standard alternate
minima for that approach, then I guess it would make a difference. But
I've never seen one WITH standard alternate minima, so it really IS an
academic exercise under part 91.
But I think I see some relevance now, believe it or not -- In my
carrier's 121 Ops Specs, we use completely different alternate minima
from what's on the plate. Ours comes from a calculation based on
adding (feet & vis) to the actual minima for the approaches at that
airport. The alternate minima on the plate are pretty much irrelevant,
other than an "NA" being in the block. (Yeah, it pretty much went over
everybody's head the first time they went over it in ground school.
Telling me to forget what I've been doing for the past 6 years isn't so
easy!)
How many feet you add to that approach depends on ... you guessed it
... whether or not it's a precision or nonprecision approach. The Ops
Specs, at the beginning of the section, go on to list all the types of
approaches we're authorized to do, under two subheadings: Nonprecision
Approaches, and Precision Approaches Other Than Cat II and III. The
only things under the Precision column are ILS and ILS/DME. No
mention of an LDA with Glideslope; only LDA and LDA/DME, both under the
Nonprecision category.
Learn something new every day, I guess. But I still think it's a
stupid question to ask at an interview. :-)
Thanks very much for your response.
Jeff G
<gar...@netstreet.net> wrote:
>OK, I'm in need of some 100% trivial information. I have a friend
>going for an airline interview next week, and rumor has it they're
>going to whip out an approach plate with an "LDA with Glideslope"
>approach.
Going to ACA, eh? They like that one.
>Nothing really unusual about such a beast... it's basically just an ILS
>offset from the runway by more than a couple degrees, and [other than
>turning before you land] is flown the same way, complete with a
>Decision Altitude (DA) vs. an MDA. In this case, I think it'll
>probably be the one to Runway 6 in Roanoke, VA (ROA).
From all accounts, yep, that's the one they'll whip out.
>The tricky part: I hear the question will be, "Is this a precision
>approach?"
>
>
>I find conflicting information in the FAR and AIM. My answer would
>have to be yes, based on the definition found both in FAR 1.1 and in
>the Pilot/Controller glossary: "A precision approach is a standard
>instrument approach procedure in which an electronic glide slope is
>provider, such as ILS and PAR."
>
>That seems pretty cut and dry to me, but then I was pointed to the AIM,
>section 5-4-5-(a)-5:
>
>"TERPS criteria are provided for the following type of instrument
>approach procedures:
>
> (a) Precision approaches where an electronic glide slope is provided
>(PAR and ILS) and,
>
> (b) Nonprecision approaches where glide slope information is not
>provided (*all* approaches except PAR and ILS)." [emphasis mine]
>
>
>I'd say the preponderance of the evidence leans toward an LDA/GS being
>a precision approach (by its definition in 1.1), but I'd appreciate
>your thoughts.
In the not too distant past, a debate was raging on the ProPilot BBS
on just this issue. I for one argued that it was a precision
approach, citing your exact reasoning. But as it turns out, I was
wrong. According to TERPS criteria, which are the only criteria that
really matter when you get right down to it, a LDA/GS approach is a
*non-precision* approach in spite of the electronic glideslope and the
DA. This straight from the TERPS-meister, Wally Roberts.
But, this is really a purely academic BS question from a flying
standpoint, since a LDA/GS approach is flown exactly like an ILS
approach, right up until you break out. Then you just make a gentle
turn to line up and land. It's a nonissue for (part 91) alternate
minimums as well (600 ft vs 800 ft) since at places like ROA, the
alternate mins are typically nonstandard.
>Why such a question would be asked of an applicant, I don't know (other
>than to see if he knows where to find things in the FAR/AIM), but it's
>got my curiosity piqued.
>
>Thanks in advance.
I don't know where they come up with this BS either, but then again,
I'm not an interviewer. If I ever become one, I'll tell you, but then
I couldn't hire you. :) But some interviewers like to pile on
questions, intentionally looking to put pressure on you to see how
you'll react to something you haven't prepared for and don't know.
This probably falls under that category.
Jeff G
wb...@mciworld.com
guidance to the runway, I would classify it as a precision approach.
Approaches giving only horozontal navigation guidance are non-precision.
Subject: Is an LDA w/GS a "Precision" approach?
Date: Wed, 01 Sep 1999 18:39:55 -0400
From: Garner Miller <gar...@netstreet.net>
Organization: US Airways Express - http://www.usairways.com/
Newsgroups: rec.aviation.ifr
OK, I'm in need of some 100% trivial information. I have a friend
going for an airline interview next week, and rumor has it they're
going to whip out an approach plate with an "LDA with Glideslope"
approach.
Nothing really unusual about such a beast... it's basically just an ILS
offset from the runway by more than a couple degrees, and [other than
turning before you land] is flown the same way, complete with a
Decision Altitude (DA) vs. an MDA. In this case, I think it'll
probably be the one to Runway 6 in Roanoke, VA (ROA).
The tricky part: I hear the question will be, "Is this a precision
approach?"
I find conflicting information in the FAR and AIM. My answer would
have to be yes, based on the definition found both in FAR 1.1 and in
the Pilot/Controller glossary: "A precision approach is a standard
instrument approach procedure in which an electronic glide slope is
provider, such as ILS and PAR."
That seems pretty cut and dry to me, but then I was pointed to the AIM,
section 5-4-5-(a)-5:
"TERPS criteria are provided for the following type of instrument
approach procedures:
(a) Precision approaches where an electronic glide slope is provided
(PAR and ILS) and,
(b) Nonprecision approaches where glide slope information is not
provided (*all* approaches except PAR and ILS)." [emphasis mine]
I'd say the preponderance of the evidence leans toward an LDA/GS being
a precision approach (by its definition in 1.1), but I'd appreciate
your thoughts.
Why such a question would be asked of an applicant, I don't know (other
than to see if he knows where to find things in the FAR/AIM), but it's
got my curiosity piqued.
Thanks in advance.
--
Gene Hudson
>
> OK, I'm in need of some 100% trivial information. I have a friend
> going for an airline interview next week, and rumor has it they're
> going to whip out an approach plate with an "LDA with Glideslope"
> approach.
>
> a precision approach (by its definition in 1.1), but I'd appreciate
> your thoughts.
I have had extensive discussions with the FAA and several examiners over
this exact issue. The bottom line is as follows:
The FAR 1.1 definition is, in the FAA's opinion, incomplete. They
maintain that in order for an approach to be a precision approach it
must end at a decision height, not an MDA. Thus, even an ILS is a
non-precision approach if you must, due to wind, circle to land to
another runway.
Having said this, not one FAA person can point to a reference that
clearly states that this is true. All of them refer to TERPS, but no
one can show me the words. One airspace specialist got hot under the
collar when I asked him for the exact reference. He said it was
unreasonable for us to expect that the FAA put *everything* down in
writing.
So, we are left with the current state of things: according to FAR 1.1,
any approach with electronic glideslope guidance is a precision
approach; while, according to the FAA (who writes the violations), only
approaches with a GS and ending in a DA (decision altitude) are
precision approaches. According to the FAA, and LDA/GS, or an ILS
circle to land, are not precision approaches.
I would be delighted if someone, anyone, could support this (FAA)
position with a real reference. I have a TERPS, and I do not see where
they get this interpretation.
Regards,
Gene Hudson
CFI, CFII, MEI, ASC, 7000TT
Daniel Delaney
approach.
Regards,
Danny.
Garner Miller <gar...@netstreet.net> wrote in message
news:010919991839556196%gar...@netstreet.net...
> OK, I'm in need of some 100% trivial information. I have a friend
> going for an airline interview next week, and rumor has it they're
> going to whip out an approach plate with an "LDA with Glideslope"
> approach.
>
> Nothing really unusual about such a beast... it's basically just an ILS
> offset from the runway by more than a couple degrees, and [other than
> turning before you land] is flown the same way, complete with a
> Decision Altitude (DA) vs. an MDA. In this case, I think it'll
> probably be the one to Runway 6 in Roanoke, VA (ROA).
>
>
> The tricky part: I hear the question will be, "Is this a precision
> approach?"
>
>
> I find conflicting information in the FAR and AIM. My answer would
> have to be yes, based on the definition found both in FAR 1.1 and in
> the Pilot/Controller glossary: "A precision approach is a standard
> instrument approach procedure in which an electronic glide slope is
> provider, such as ILS and PAR."
>
> That seems pretty cut and dry to me, but then I was pointed to the AIM,
> section 5-4-5-(a)-5:
>
> "TERPS criteria are provided for the following type of instrument
> approach procedures:
>
> (a) Precision approaches where an electronic glide slope is provided
> (PAR and ILS) and,
>
> (b) Nonprecision approaches where glide slope information is not
> provided (*all* approaches except PAR and ILS)." [emphasis mine]
>
>
> I'd say the preponderance of the evidence leans toward an LDA/GS being
> a precision approach (by its definition in 1.1), but I'd appreciate
> your thoughts.
>
>
David Stocker
very interesting example (see plate at
<http://rev.net/~stockerd/images/Aviation/ROA_LDA_6.pdf>). The straight-in
LDA 6 has the lowest minimums of any approach at ROA, including the
straight-in ILS 33! (364 vs. 500 AGL) All approaches at ROA have higher than
normal minimums due to terrain restrictions for the missed approach. LDA 6 is
offset from the runway heading by about 13 deg. due to a mountain approx. 2800
AGL on the runway heading.
I was in the tower one night watching the airliners break out near minimums
and make the honker turn required to land. Impressive! Not too long ago I
was on a US 737 which missed on this approach during rain showers -- made it
on the second try. I would think that that relatively low minimum, required
turn and runway length (6800) make this one of the toughest approaches
routinely flown by the airlines on the East Coast.
For me, this approach settles the "can I descend on the GS before I'm
established on the localizer" debate. Do that on this approach and you'll
likely hit a granite cloud -- note that ridges on both sides as shown on the
plate (3375 MSL on the left, 4011 on the right).
My answer to the interview question would be "If straight-in it's a precision
approach, otherwise it's not."
Dave Stocker
sto...@rev.net
PP-ASEL-IA, PA28-181, N8331C
Garner Miller <gar...@netstreet.net> wrote:
>
>OK, I'm in need of some 100% trivial information. I have a friend
>going for an airline interview next week, and rumor has it they're
>going to whip out an approach plate with an "LDA with Glideslope"
>approach.
>
>Nothing really unusual about such a beast... it's basically just an ILS
>offset from the runway by more than a couple degrees, and [other than
>turning before you land] is flown the same way, complete with a
>Decision Altitude (DA) vs. an MDA. In this case, I think it'll
>probably be the one to Runway 6 in Roanoke, VA (ROA).
>
>The tricky part: I hear the question will be, "Is this a precision
>approach?"
>
>[...snip...]
Bubba F. Booey
"Daniel Delaney" <Dan...@delaney.flyer.co.uk> wrote:
> If the localiser is offset by more than 30° then it would be
> a circling approach.
We call it a localizer over here in US of A and
instrument approaches can be either precision or
non-precision. It's minimums that are classified
into circling or straight-in.
Bubba F. Booey
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> >
> > OK, I'm in need of some 100% trivial information. I have a friend
> > going for an airline interview next week, and rumor has it they're
> > going to whip out an approach plate with an "LDA with Glideslope"
> > approach.
> >
> > a precision approach (by its definition in 1.1), but I'd appreciate
> > your thoughts.
>
>
>